The present invention relates to self-contained actuator systems and, in particular, it concerns a self-contained hydraulic linear actuator system having a pump, the pumping assembly of which is adjustable so as to control the speed and direction of the fluid flow through the system and a linear actuator responsive to the fluid flow.
Self-contained hydraulic actuator systems having closed hydraulic systems incorporating bi-directional pumps are known in the art. Heretofore, these systems required bi-directional motors to drive the pump. Therefore, the speed and direction of pump rotation, and thus fluid flow through the system, is the direct result of the movement of the motor driving the pump. The motors best suited for this purpose are electrical servomotors, which provide the ability to change speed and direction quickly as required. This is particularly relevant in the field of motion simulation.
There are a number of drawbacks associated with the use of servomotors to drive bi-directional pumps. One major drawback is that bi-directional servomotors are expensive since they must be built to perform, and withstand the rigors of, substantially instantaneous changes of speed and/or direction numerous times during the performance of a task.
There is therefore a need for a self-contained hydraulic linear actuator system having a pump, the pumping assembly of which is adjustable so as to control the speed and direction of the fluid flow through the system and a linear actuator responsive to the fluid flow. It would be advantageous if the system included a closed hydraulic system.